1. Field of the Invention
The present invention relates to an oxygen absorbing member having an oxygen absorbing property and formed into a sheet like shape, and a method for manufacture thereof. The oxygen absorbing member can be used in the field of a container storing foodstuffs or pharmaceuticals. Oxygen existing in the container can be removed by securing this oxygen absorbing member in the container, and thus deterioration or oxidation of foodstuffs or pharmaceuticals can be prevented.
2. Description of Related Art
In order to maintain quality or freshness of foodstuffs or pharmaceuticals during their storage period, so-called oxygen absorbing packaging, wherein an oxygen absorbing agent is enclosed in the container together with articles to be stored, has been widely used for the purpose of absorbing oxygen existing in a package. This oxygen absorbing packaging may prevent articles from deteriorating due to an influence of oxygen or eroding due to microbes under the existence of oxygen.
Therefore, various packages of articles delivered to general consumers generally contain an oxygen absorbing agent.
The oxygen absorbing packaging can be attained by enclosing foodstuffs, pharmaceuticals or the like to be stored in a container having a property of blocking permeation of a gas together with oxygen absorbing member in which oxygen absorbing agent is contained. Generally, this oxygen absorbing member is supplied in the form of a small bag of gas permeable packaging member containing oxygen absorbing composition in granular or powder shape.
In many cases, it is desired that such a small bag of oxygen absorbing agent (sometimes simply referred to as a "small bag") is secured to an inside surface of a container. Thereby, an oxygen absorbing agent is prevented from being mixed in and eaten with articles (foodstuff), or being accidentally cooked with articles.
Various methods of securing this small bag are proposed. Generally, small bags are attached to an inner wall surface of packaging members, such as packaging bags or containers (carton, box, etc.) by use of an adhesive agent, a hot melt agent or a pressure sensitive adhesive double coated tapes.
However, it is also difficult, in many cases, to sufficiently secure the small bag to a container because the surface of the small bag is often uneven and the small bag is swollen. If a small bag is secured to a container by any chance, it is often secured to a container in part, but not entire surface of a small bag.
As a result, the area of a small bag not in contact with the surface of a container creates a gap. Such a gap causes various problems, namely, stored articles are jammed in or hooked at the gap, and thus smooth handling of the articles can be disturbed or the small bag falls off from the container.
Moreover, a conventional oxygen absorbing member using powdery oxygen absorbing composition has a problem in that the powder sprays in the air when it is to be filled in the gas permeable packaging member and thus a part of the powder adheres to the surface of the small bag.
Then, it was proposed to have a container itself having oxygen absorbing property. In the Japanese Patent (Kokoku) Publication No. 62-1824 and the Japanese Patent (Kokoku) Publication No. 4-6082, manufacturing exterior structure with a film containing an oxygen absorbing agent is disclosed.
However, the oxygen absorbing property in the prior art has been insufficient. The conventional packaging member has further problems in that since packaging of a bag or container itself is manufactured by using a special packaging member, the cost of the container increases which leads to an increase in the price of the articles.
In the Japanese Patent Laid-Open Publications Nos. 2-86758, 54-114585, 55-44344, 56-26524, the Japanese Utility Model Laid-Open Publication No. 60-10768, the Japanese Patent Laid-Open Publications Nos. 55-109428 and 55-109428, forming an oxygen absorbing agent in a sheet like shape is disclosed. The prior art also discloses the prevention of exposure of a surface of the sheet shaped oxygen absorbing agent by covering the agent by a wrapping material. Thus, direct contact of the oxygen absorbing agent and foodstuff is prevented.
Since the sheet shaped oxygen absorbing agent is not a granule or powder, it is advantageous in that no leakage of granule or powder within the package is likely to happen due to destruction of the package, unlike the case of the conventional oxygen absorbing member in a small bag.
When this sheet shaped oxygen absorbing member is attached to a container, the method of cutting the sheet in a predetermined size and then adhering the sheet to a predetermined place in the container by using adhesive agent can be considered. If this method is applied, the side edge of the oxygen absorbing layer is exposed to the atmosphere when the sheet is cut out. In this case, the above-mentioned direct contact occurs, and it is burdensome to apply adhesive to the sheet so cut out. Moreover, the conventional sheet shaped oxygen absorbing agent has a problem in that its oxygen absorbing property is rather weak.